Reactivity of surface groups attached on a plasma treated poly(propylene) film. Application to a new concept of a chelating membrane

Abstract

The goal of the present work is the synthesis of a new chelating membrane from a trivial material, such as poly(propylene), through the fixation of the chelating groups after a cold plasma irradiation. The cold plasma treatment compared to the electron beam irradiation is less degrading since only a few layers are affected. It leads to a surface bearing two types of reactive species: radicals able to initiate a post-grafting reaction of any kind of vinyl monomer and new surface functional groups – depending on the chemical nature of the cold plasma – able to react with a chelating molecule. So the modulation of the plasma conditions and the choice of the attached chelating groups onto the material can control the chelating capacity of such irradiated material. The nitrogen plasma modification of poly(propylene) (PP) leads to a weakly cross-linked and slightly degraded surface bearing alkyl radicals and amino groups in various densities depending on plasma conditions. After the plasma irradiation, N-acryloylglycine (NAG) and diethylenetriaminepentaacetic acid (DTPA) possessing specific chelating properties are grafted successfully onto the PP surface in different ways. All the grafted films present an important selectivity towards silver ions and consequently towards soft metallic ions, too. The ion capacity of NAG grafted films remains higher than with DTPA whatever the density of amino groups attached on the surface is.